System and a method for determining an image rejection characteristic of a receiver within a transceiver

Abstract

A method for determining an image rejection characteristic of a receiver within a transceiver is provided. The transceiver uses a common local oscillator. The method includes generating a test signal having a spectral peak and generating a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak. Further, the method includes down-mixing the test signal in the receiver using the local oscillator signal to generate a down-mixed signal. The method further includes calculating a first value of a signal characteristic of the down-mixed signal in a first frequency range corresponding to a desired signal component of the down-mixed signal and calculating a second value of the signal characteristic of the down-mixed signal in a second frequency range corresponding to an undesired signal component of the down-mixed signal. Further, the method includes comparing the first value and the second value to generate the image rejection characteristic.

What is claimed is: 
     
       1. A method for determining an image rejection characteristic of a receiver within a transceiver using a common local oscillator, comprising:
 generating a test signal having a spectral peak; 
 generating a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak; 
 down-mixing the test signal in the receiver using the local oscillator signal to generate a down-mixed signal; 
 calculating a first value of a signal characteristic of the down-mixed signal in a first frequency range corresponding to a desired signal component of the down-mixed signal; 
 calculating a second value of the signal characteristic of the down-mixed signal in a second frequency range corresponding to an undesired signal component of the down-mixed signal; and 
 comparing the first value and the second value to generate the image rejection characteristic. 
 
     
     
       2. The method of  claim 1 , wherein a center frequency of the first frequency range has an offset from an intermediate frequency, and wherein the second frequency range is mirror-inverted to the first frequency range with respect to the intermediate frequency. 
     
     
       3. The method of  claim 2 , wherein the intermediate frequency is zero. 
     
     
       4. The method of  claim 1 , wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of the local oscillator signal. 
     
     
       5. The method of  claim 4 , wherein the test signal comprises a plurality of equidistant spectral peaks. 
     
     
       6. The method of  claim 1 , wherein the first value of the signal characteristic is related to an energy of the down-mixed signal in the first frequency range and the second value of the signal characteristic is related to an energy of the down-mixed signal in the second frequency range. 
     
     
       7. The method of  claim 1 , wherein comparing the first value of the signal characteristic and the second value of the signal characteristic comprises calculating a ratio of the first value of the signal characteristic and the second value of the signal characteristic. 
     
     
       8. A method for determining an image rejection characteristic of a receiver within a transceiver using a common local oscillator, comprising:
 generating a test signal having a spectral peak, a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak and a second local oscillator signal comprising a frequency being mirror-inverted to the local oscillator signal with respect to the center frequency of the spectral peak; 
 down-mixing the test signal in the receiver using the local oscillator signal to generate a down-mixed signal and down-mixing the test signal in the receiver using the second local oscillator signal to generate a second down-mixed signal; 
 calculating a value of a signal characteristic of the down-mixed signal and a value of the signal characteristic of the second down-mixed signal in a frequency range corresponding to a desired signal component of the down-mixed signal; and 
 comparing the value of the signal characteristic of the down-mixed signal and the value of the signal characteristic of the second down-mixed signal to generate the image rejection characteristic. 
 
     
     
       9. The method of  claim 8 , wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of the local oscillator signal, and wherein the test signal does not have another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of second local oscillator signal. 
     
     
       10. The method of  claim 9 , wherein the test signal comprises a plurality of equidistant spectral peaks. 
     
     
       11. The method of  claim 8 , wherein the value of the signal characteristic of the down-mixed signal is related to an energy of the down-mixed signal in the frequency range and the value of the signal characteristic of the second down-mixed signal is related to an energy of the second down-mixed signal in the frequency range. 
     
     
       12. The method of  claim 8 , wherein comparing the value of the signal characteristic of the down-mixed signal and the value of the signal characteristic of the second down-mixed signal comprises calculating a ratio of the value of the signal characteristic of the down-mixed signal and the value of the signal characteristic of the second down-mixed signal. 
     
     
       13. A system for determining an image rejection characteristic of a receiver within a transceiver using a common local oscillator, comprising:
 a signal generator configured to generate a test signal having a spectral peak; 
 wherein the local oscillator is configured to generate a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak, wherein the receiver is configured to down-mix the test signal using the local oscillator signal to generate a down-mixed signal, and 
 an analysis unit configured to calculate a first value of a signal characteristic of the down-mixed signal in a first frequency range corresponding to a desired signal component of the down-mixed signal, to calculate a second value of the signal characteristic of the down-mixed signal in a second frequency range corresponding to an undesired signal component of the down-mixed signal, and to compare the first value and the second value to generate the image rejection characteristic. 
 
     
     
       14. The system of  claim 13 , wherein a center frequency of the first frequency range has an offset from an intermediate frequency, and wherein the second frequency range is mirror-inverted to the first frequency range with respect to the intermediate frequency. 
     
     
       15. The system of  claim 14 , wherein the intermediate frequency is zero. 
     
     
       16. The system of  claim 13 , wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of the local oscillator signal. 
     
     
       17. The system of  claim 16 , wherein the test signal comprises a plurality of equidistant spectral peaks. 
     
     
       18. The system of  claim 13 , wherein the first value of the signal characteristic is related to an energy of the down-mixed signal in the first frequency range and the second value of the signal characteristic is related to an energy of the down-mixed signal in the second frequency range. 
     
     
       19. The system of  claim 13 , wherein the analysis unit is configured to compare the first value of the signal characteristic and the second value of the signal characteristic by calculating a ratio of the first value of the signal characteristic and the second value of the signal characteristic. 
     
     
       20. The system of  claim 13 , wherein the signal generator comprises a frequency multiplier configured to generate the test signal by multiplying a frequency of a reference signal used for the local oscillator. 
     
     
       21. A system for determining an image rejection characteristic of a receiver within a transceiver using a common local oscillator, comprising:
 a signal generator configured to generate a test signal having a spectral peak; 
 wherein the local oscillator is configured to generate a local oscillator signal comprising a frequency with an offset from a center frequency of the spectral peak and a second local oscillator signal comprising a frequency being mirror-inverted to the frequency of the local oscillator signal with respect to the center frequency of the spectral peak, 
 wherein the receiver is configured to down-mix the test signal using the local oscillator signal to generate a down-mixed signal and to down-mix the test signal using the second local oscillator signal to generate a second down-mixed signal, and 
 an analysis unit configured to calculate a value of a signal characteristic of the down-mixed signal and a value of the signal characteristic of the second down-mixed signal in a frequency range corresponding to a desired signal component of the down-mixed signal, and to compare the values of the signal characteristic of the down-mixed signal and the second down-mixed signal to generate the image rejection characteristic. 
 
     
     
       22. The system of  claim 21 , wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of the local oscillator signal, and wherein the test signal omits another spectral peak being mirror-inverted to the spectral peak with respect to the frequency of second local oscillator signal. 
     
     
       23. The system of  claim 22 , wherein the test signal comprises a plurality of equidistant spectral peaks. 
     
     
       24. The system of  claim 21 , wherein the value of the signal characteristic of the down-mixed signal is related to an energy of the down-mixed signal in the frequency range and the value of the signal characteristic of the second down-mixed signal is related to an energy of the second down-mixed signal in the frequency range. 
     
     
       25. The system of  claim 21 , wherein the signal generator comprises a frequency multiplier configured to generate the test signal by multiplying a frequency of a reference signal used for the local oscillator.